package org.flint.summary.leetcode;

/**
 * @author flint92
 */
public class NumberOfOneBits_191 {

    /**
     * Write a function that takes an unsigned integer
     * and return the number of '1' bits it has (also known as the Hamming weight).
     * <p>
     * Example 1:
     * <p>
     * Input: 00000000000000000000000000001011
     * Output: 3
     * Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.
     * Example 2:
     * <p>
     * Input: 00000000000000000000000010000000
     * Output: 1
     * Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.
     * Example 3:
     * <p>
     * Input: 11111111111111111111111111111101
     * Output: 31
     * Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.
     * <p>
     * <p>
     * Note:
     * <p>
     * Note that in some languages such as Java, there is no unsigned integer type.
     * In this case, the input will be given as signed integer type and should not affect your implementation,
     * as the internal binary representation of the integer is the same whether it is signed or unsigned.
     * In Java, the compiler represents the signed integers using 2's complement notation.
     * Therefore, in Example 3 above the input represents the signed integer -3.
     * <p>
     * you should treat n as an unsigned value
     */
    public int hammingWeight(int n) {
        int count = 0;
        while (n != 0) {
            count++;
            n = n & (n - 1);
        }
        return count;
    }

}
